A Half Century of Bridges – Dumbarton Bridge

October 2, 2015 | By | Reply More

Dumbarton_Bridge_CA_from_the_airThe fame of the two biggest bridges has eclipsed the fact that the bay had been spanned several times previously and that new crossings are still being constructed.

The San Francisco Bay’s first bridge was a railroad trestle built in 1906 by the Southern Pacific at the narrow of the shallow southern part of the bay between Dumbarton Point and the Palo Alto area.

The bridge has never been officially named, but its commonly used name comes from Dumbarton Point, named in 1876 after Dumbarton, Scotland.

Built originally to provide a shortcut for traffic originating in San Mateo and Santa Clara counties, the bridge served industrial and residential areas on both sides.

dumbartonThe first automobiles to cross the bay under their own power chugged jubilantly over the new low-level, three mile Dumbarton automobile bridge just north of the S.P. trestle, on January 17 of 1927.

The original bridge was built with private capital and then purchased by the state for $2.5 million in 1951.

Although it was constructed as a drawbridge to allow passage for ships to the far end of the bay, the only vessels sailing in that area – aside from an occasional barge – were small boats from yacht harbors at Palo Alto and Alviso.

For many years, whenever there was a large northward migration of these craft, such as on the occasions when the California –Stanford Big Game was held in Berkeley, bridge attendants were kept buy hoisting the lift span to allow the passage of each sailboat, then lowering it again to accommodate the irate honking motorists bound for the same event.

old-and-new-Dumbarton-BridgeThe bottleneck was finally broken when the yacht clubs agreed to convoy their vessels through in a single group.

In the 1970’s, its age and the two-lane undivided roadway and lift-span led to a replacement bridge, built to the north.

When the current bridge was planned in the 1970s, Caltrans conducted extensive environmental research on the aquatic and terrestrial environment.

The area around the bridge is an important ecological area, hosting many species of birds, fish and mammals. 

On both sides of the east end of the bridge are large salt ponds and levee trails belonging to the Don Edwards San Francisco Bay National Wildlife Refuge.

1983-Dumbarton-BridgeIt was rebuilt in 1984 for safety and traffic congestion reasons.  Portions of the old drawbridge remain as fishing piers.

The center span of the original bridge was demolished in a controlled explosion in September 1984.

The structure was re-striped to accommodate six lanes on October 18, 1989 in response to the temporary closing of the San Francisco – Oakland Bay Bridge due to the Loma Prieta earthquake, and the permanent widening of the approaches was completed by July 2003.

The cost of the complete replacement project was $200 million. The current bridge includes a two-way bicycle and separate pedestrian path on the south-facing side.

The Dumbarton now provides three lanes in each direction, separated by a concrete barrier, as well as a bicycle/pedestrian path. Today it carries over 81,000 vehicles per day, and is the shortest bridge across San Francisco Bay at 1.63 miles.

1024px-Dumbarton_Bridge1Just to the south of the car bridge lies the old Dumbarton Rail Bridge.

Built in 1910, the rail bridge has been unused since 1982 and its western approach collapsed in a fire in 1998.

When the bridge was in use, boaters would signal the operator, who would start a diesel engine and rotate the bridge to the open position on a large gear.

Today the bridge is now left in the open position.

There are plans for a new rail bridge and rehabilitation of the rail line to serve a commuter rail service to connect Union City, Fremont, and Newark to various Peninsula destinations.


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Category: Fog City - City of Fog, San Francisco Bay

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